1. Field of the Invention
The present invention relates to a display device that can be modulated in its optical characteristics by voltage, current, frequency and other electric factors, and to a display device correction system. More particularly, the present invention relates to a projection type display device in which an element such as a thin film transistor (TFT) is provided for every display pixel.
2. Description of the Related Art
Recently, a technique has been rapidly developed which relates to fabrication of a semiconductor device, such as a thin film transistor (TFT), having a semiconductor thin film formed on an insulating substrate. This is caused by an increasing demand for a liquid crystal display device of active matrix type (liquid crystal panel).
A liquid crystal display device of active matrix type (liquid crystal panel) has an great advantage, over CRT, that it can provide a larger screen (of size 40 to 100) at lower cost and can also provide an image with higher resolution to an observer.
Projectors using such a liquid crystal panel (front projectors, rear projectors, etc.) have been increasingly developed in recent years. In a front projector, light from a light source is irradiated onto a liquid crystal panel to form an image on a reflection type screen, whereby the reflected light from the screen is provided as an image to a user. In a rear projector, on the other hand, light from a light source is irradiated onto a liquid crystal panel to form an image on the surface of a transmission type diffuser screen (hereinafter, may simply be referred to as a xe2x80x9cscreenxe2x80x9d), thereby allowing an image to be observed from the screen face side that is opposed to the light source.
Such projectors include a transmission type single-panel model using a single panel capable of multicolor display of RGB, and a triple-panel model in which three kinds of monochrome display panels each corresponding to the color R, G and B are used to optically synthesize those three kinds of monochrome screens.
The display panels both for the single-panel model and the triple-panel model have basically the same structure except that the monochrome display panel is comprised of pixels all of which are devoted to the only one of the primary RGB colors consisting of three colors of R, G and B, while the multicolor display panel is comprised of pixels to which the respective primary RGB colors are allocated.
In the transmission type display panel for use in projectors etc., which utilizes as an electro-optic substance the liquid crystal (or the like), the relationship between optical modulation rate thereof and voltage level of video signals is nonlinear. Further, nonlinearity is different in the primary color of R, G and B in dependence upon dispersion characteristic or the like of the liquid crystal. In order to pre-correct this nonlinearity, a gamma correction circuit is incorporated in an IC chip or a peripheral driver circuit.
In a conventional projector, as shown in FIG. 3, at the time of shipment, in which an image displayed on a screen 14 is measured from the front by a measurement device such as a CCD 11, and a part of the resultant image data is stored in a memory to write gamma correction data based on that stored data into a gamma correction memory. This writing operation into the gamma correction memory is performed only once at the time of shipment of the device. In other words, conventionally, gamma correction data written into the memory at the time of shipment is not rewritten thereafter.
In the conventional projectors, keeping good display performance has been impossible because of change of the image quality caused by degradation in a light source, a liquid crystal panel and a polarizer which would be arisen from use over hours. Such degradation has been a serious problem in that degradation in the liquid crystal panel and the polarizer which would be mainly brings about lowering of the contrast ratio and degradation in the light source mainly incurs a deterioration in the display characteristics (reproducibility of color, brightness).
Also, demanded performance level of projectors is getting higher day by day, which promotes enhancement, increasing display pixels in number, of liquid crystal panels in terms of fineness and density.
Thus, the problem to be addressed in a projector and a system including the same is designed to maintain the display of high image quality and fine quality for hours.
The present invention has been made in view of the above, and an object of the present invention is to provide a display device and a display device correction system, which are capable of keeping for hours an excellent display characteristics.
To attain this, disclosed herein in accordance with an aspect of the present invention is:
a display device comprising a liquid crystal panel, a liquid crystal panel driver circuit and a memory, for displaying video light obtained by irradiating with light the liquid crystal panel to which a video signal is inputted, characterized in that:
the display device comprising:
a detection means for obtaining display screen data from the video light;
means for obtaining correction data on the basis of the display screen data;
means for storing the correction data in the memory;
means for correcting the video signal on the basis of the correction data stored in said memory; and
means for inputting the corrected image data to the liquid crystal panel driver circuit.
According to another aspect of the present invention, there is provided a display device comprising a light source, a liquid crystal panel and a screen, for projecting with magnification onto the screen video light obtained by irradiating with light the liquid crystal panel to which a video signal is inputted, characterized in that
the display device comprising:
a detection means for obtaining display screen data from the video light;
an arithmetic means for obtaining correction data from the display screen data;
means for storing the correction data in the memory; and
means for correcting the video signal on the basis of the correction data stored in the memory.
According to still another aspect of the present invention, there is provided a display correction system, characterized by comprising:
means for irradiating with light a display device to which a video signal is inputted, to thereby obtain video light;
a detection means for obtaining display screen data from the video light;
means for obtaining correction data on the basis of the display screen data;
means for storing the correction data in s memory;
means for correcting the video signal on the basis of the correction data to correct the video light; and
means for obtaining a display from the corrected video light.
In the above respective structures, the correction data is characterized by being a digital signal.
In the above respective structures, the memory is characterized by being a gamma correction memory.